Method and apparatus for link adaptation in precoded MIMO systems

Abstract

Embodiments of the invention relate to methods and apparatus for link adaptation in a preceded MIMO system. According to one embodiment, there is provided a method for link adaptation in a precoded MIMO system. The method comprises: receiving first channel quality information γ_CQI; with respect to at least one layer r in a plurality of layers in a link; obtaining a Hybrid Automatic Repeat Request (HARQ) scaling factor μ_r that is associated with a HARQ feedback; and interpreting the first channel quality information γ_CQI into second channel quality information {circumflex over (γ)}_r based on at least the HARQ scaling factor μ_r, wherein the second channel quality information {circumflex over (γ)}_r is for adapting the at least one layer r in the plurality of layers. According to another embodiment, there is provided an apparatus for link adaptation in a precoded MIMO system.

Description

FIELD OF THE INVENTION[0001]Embodiments of the present invention generally relate to link adaptation. More particularly, embodiments of the present invention relate to methods and apparatuses for link adaptation in a precoded multiple-input multiple-output (MIMO) system.BACKGROUND OF THE INVENTION[0002]In the technical field of wireless communication, channel fading is a fundamental characteristic of a wireless communication channel. Meanwhile, channel fading may be variable over time of the instantaneous conditions of the wireless communication channel. Channel-dependent adaptation of a transmission is one way to handle channel fading. When a channel is in a good state, it is possible to transmit data using a low level of error protection on the channel. In contrast, when the channel is in a bad fading state, a higher level of error protection is necessary, which causes a reduction in the information data rate. The level of error protection may, for example, be varied by changing t...

AI Technical Summary

Benefits of technology

[0014]According to one embodiment of the present invention, the first adjusting unit comprises: a first increasing unit configured for increasing the HARQ scaling factor μr for everyone in the plurality of layers in response to a single-layer HARQ ACK being received; and a first decreasing unit configured for decreasing the HARQ scaling factor μr for everyone in the plurality of layers in response to a single-layer HARQ NACK being received.

[0015]According to one embodiment of the present invention, the second adjusting unit comprises: a second increasing unit configured for increasing the HARQ scaling factor μr only for layer r on which a multi-layers HARQ ACK is received in response to the multi-layers HARQ ACK being received; and a second decreasing unit configured for decreasing the HARQ scaling factor μr only for layer r on which a multi-layers HARQ NACK is received in response to the multi-layers HARQ NACK being received.

Problems solved by technology

Meanwhile, channel fading may be variable over time of the instantaneous conditions of the wireless communication channel.

In practice, the UE may be able to directly determine the instantaneous channel conditions of the channel, but the BS is not able to do so.

Although it has provided a method of estimating quality in an individual layer of a plurality of layers, delay is introduced in the estimating process.

Therefore, those methods and apparatuses cannot provide post-equalization SINR when eigen-based TM8 (Transmission Mode 8) is used in LTE TDD system.

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